The present invention relates to novel acylaminocycloalkyl compounds, in particular to the compounds of the formula I as described herein. The compounds possess valuable therapeutic properties and are suitable, in particular, for treating diseases that respond to modulation of the dopamine D3 receptor.
Neurons obtain their information by way of G protein-coupled receptors, inter alia. A large number of substances exert their effect by way of these receptors. One of them is dopamine. Confirmed findings exist with regard to the presence of dopamine and its physiological function as a neurotransmitter. Disorders in the dopaminergic transmitter system result in diseases of the central nervous system which include, for example, schizophrenia, bipolar disorders, depression, Parkinson's disease, disorders associated with drug abuse. These diseases, and others, are treated with drugs which interact with the dopamine receptors.
Up until 1990, two subtypes of dopamine receptor had been clearly defined pharmacologically, termed D1 and D2 receptors. More recently, a third subtype was found, namely, the D3 receptor which appears to mediate some effects of antipsychotics and antiparkinsonian drugs (J. C. Schwartz et al., “The Dopamine D3 Receptor as a Target for Antipsychotics” in Novel Antipsychotic Drugs, H. Y. Meltzer, ed., Raven Press, New York 1992, pages 135-144; M. Dooley et al., Drugs and Aging 1998, 12:495-514; J. N. Joyce, Pharmacology and Therapeutics 2001, 90:231-59, “The Dopamine D3 Receptor as a Therapeutic Target for Antipsychotic and Antiparkinsonian Drugs”). Since then, the dopamine receptors have been divided into two families. On the one hand, there is the D2 group, consisting of D2, D3 and D4 receptors, and, on the other hand, the D1 group, consisting of D1 and D5 receptors.
Whereas D1 and D2 receptors are widely distributed, D3 receptors appear to be expressed regioselectively. Thus, these receptors are preferentially to be found in the limbic system and the projection regions of the mesolimbic dopamine system, especially in the nucleus accumbens, but also in other regions, such as the amygdala. Because of this comparatively regioselective expression, D3 receptors are regarded as being a target having few side-effects and it is assumed that while a selective D3 ligand would have the properties of known antipsychotics, it would not have their dopamine D2 receptor-mediated neurological side-effects (P. Sokoloff et al., Arzneim. Forsch./Drug Res. 42(1):224 (1992), “Localization and Function of the D3 Dopamine Receptor”; P. Sokoloff et al., Nature, 347:146 (1990), “Molecular Cloning and Characterization of a Novel Dopamine Receptor (D3) as a Target for Neuroleptics”).
Selective Dopamine D3 receptor ligands have been suggested for the treatment of Parkinson's disease, schizophrenia, depression, motivation disturbances (amotivation) (see J. N. Joyce, Pharmacology and Therapeutics 90, 2001, 231-259; B. Levant, CNS Drugs 1999, 12, 391), for the treatment cognitive dysfunction, in particular cognitive dysfunction associated with schizophrenia or dementia (see J. Laszy et al., Psychopharmacology, 2005, 179, 567-575), for the treatment of disturbances associated with substance abuse, i.e. for the treatment of drug addiction or drug dependence (see J. N. Joyce, loc. cit. and C. A. Heidbreder, Brain Research Reviews 49, 2005, 77-105), for the treatment of anxiety (see Z. Rogoz et al., Polish Journal of Pharmacology, 2003, 55, 449-454), for the treatment of pain (see Levant et al., Neurosci. Lett. 2001, 303, 9), for the treatment of renal function disorders (see B. Mühlbauer, E. Küster, G. Luippold, Acta Physiologica Scandinavica, 2000, 168 (1), 219-223) and for the treatment of eating disorders (see S. C. Benoit, J. A. McQuade, D. J. Clegg, M. Xu, P. A. Rushing, S. C. Woods, R. J. Seeley, J. Randy, Behavioral Neuroscience, 2003, 117(1), 46-54).
WO 2006/082456 describes cyclohexylamides, which are Dopamine D3, D2 and HT1A antagonists. The cycloalkyl moiety of the compounds of WO 2006/082456 carries an alkylene-N-piperazinyl radical, where the other nitrogen carries a phenyl radical having a fused saturated carbocyclic radical.
Similar compounds are also known from WO 2007/148208, where the fused carbobicyclic radical is replaced by unsubstituted or substituted aryl or hetaryl and where the acyl group requires to be substituted.
Similar compounds are also known from US2009/143398, where the carbobicyclic radical is replaced by a 5,6-dichloro-2-amino-4-pyrimidyl radical.
Similar compounds are also known from WO 2011/161009 and WO 2012/004206, where the carbobicyclic radical is replaced by a 5,6-disubstituted 2-pyridyl radical having a fused heterocycle.
Compounds having a heteroaromatic ring, which is bound via a linker to a piperazine radical carrying a 1-(4-pyrimidinyl)-piperazinyl radical receptor have been described previously in WO 2004/080981, WO2004/108706, WO 2005/118558, WO 2005/118571, WO 2006/015842 and WO 2009/056625. The compounds possess high affinities for the dopamine D3 receptor, and have therefore been proposed as being suitable for treating diseases of the central nervous system.
Although some of the compounds of prior art are known to have high affinities for the Dopamine D3 receptor of less than 10 nM, there is still an ongoing need for compounds which selectively bind to the Dopamine D3 receptor. In particular, there is an ongoing need for compounds which have one of the following characteristics:                i. Selective binding to the Dopamine D3 receptor, in particular vis-à-vis binding to the Dopamine D2 receptor, adrenergic receptors such as alpha-1 or alpha-2 receptors or serotonine type receptors such as serotoninergic HT1 and 5HT2 receptors;        ii. metabolic stability, in particular microsomal stability, e.g. measured in vitro, in liver microsomes from various species (e.g. rat or human) in human cells, such as hepatocytes;        iii. no or only low inhibition of cytochrome P450 (CYP) enzymes: cytochrome P450 (CYP) is the name for a superfamily of heme proteins having enzymatic activity (oxidase). They are also particularly important for the degradation (metabolism) of foreign substances such as drugs or xenobiotics in mammalian organisms. The principal representatives of the types and subtypes of CYP in the human body are: CYP 1A2, CYP 2C9, CYP 2D6 and CYP 3A4. If CYP 3A4 inhibitors (e.g. grapefruit juice, cimetidine, erythromycin) are used at the same time as medicinal substances which are degraded by this enzyme system and thus compete for the same binding site on the enzyme, the degradation thereof may be slowed down and thus effects and side effects of the administered medicinal substance may be undesirably enhanced;        iv. a suitable solubility in water (in mg/ml);        v. suitable pharmacokinetics (time course of the concentration of the compound of the invention in plasma or in tissue, for example brain). The pharmacokinetics can be described by the following parameters: half-life, volume of distribution (in l·kg−1), plasma clearance (in l·h−1·kg−1), AUC (area under the curve, area under the concentration-time curve (in ng·h·l−1), oral bioavailability, (the dose-normalized ratio of AUC after oral administration and AUC after intravenous administration), the so-called brain-plasma ratio (the ratio of AUC in brain tissue and AUC in plasma);        vi. no or only low blockade of the hERG channel: compounds which block the hERG channel may cause a prolongation of the QT interval and thus lead to serious disturbances of cardiac rhythm (for example so-called “torsade de pointes”). The potential of compounds to block the hERG channel can be determined by means of the displacement assay with radiolabelled dofetilide which is described in the literature (G. J. Diaz et al., Journal of Pharmacological and Toxicological Methods, 50 (2004), 187-199). A smaller IC50 in this dofetilide assay means a greater probability of potent hERG blockade. In addition, the blockade of the hERG channel can be measured by electrophysiological experiments on cells which have been transfected with the hERG channel, by so-called whole-cell patch clamping (G. J. Diaz et al., Journal of Pharmacological and Toxicological Methods, 50 (2004), 187-199);        vii. high free fraction in brain, i.e. the fraction of the compound bound to proteins should be low;        viii. low lipophilicity.        